meson.build: remove version check before setting up devenv
Since 2eed279c wireplumber requires at least meson 0.59.0,
and the devenv feature is available since 0.58.0, the version check
before adding the devenv is no longer needed. Remove it.
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Since 2eed279c wireplumber requires at least meson 0.59.0,
and the devenv feature is available since 0.58.0, the version check
before adding the devenv is no longer needed. Remove it.